The Appalachian mountains are seldom mentioned among the world's great mountain ranges. Consisting mostly of low gentle ridges, when compared with the snow-capped peaks of the Himalaya, Andes, or Alps many would hesitate to call them mountains at all. But they are a large and ancient range, stretching over 1500 miles along the eastern portion of North America. The time of their formation has been dated back to the Paleozoic, with major uprisings occurring 650 million years ago. Then, about 460 million years ago, during the Ordovician period, they were the site of one of the most violent volcanic outbursts in Earth's history. New research reveals that, following that bout of vulcanism, weathering of Appalachian rock may have triggered one of Earth's major ice ages—a relatively brief frigid period that ultimately killed two-thirds of all species on the planet.
A new study has confirmed the astronomical theory of the ice ages, but with a new twist: The shutoff of the meridional ocean circulation, or MOC, and an associated southward shift of tropical monsoon rain belts seems to play an integral role in the melting of glacial period ice sheets. These changes cause warming of the Southern Hemisphere and a rise in atmospheric CO2 levels, which in turn provides a positive feedback loop that helps drive glacial termination. This is why, every 100,000 years or so, the great Northern Hemisphere ice sheets collapse and glacial conditions give way to a warm interglacial period, such as the Holocene warming humanity is currently enjoying. This, however, does not support recent claims that global warming is causing the Southeast Asian monsoon to fail.
Despite recent attempts to revive the discredited “hockey stick” temperature graph, invented by Michael Mann and promulgated by the IPCC, new research on tropical glaciers has once again shown that supposed temperature history to be bogus. While the role of the tropics in climate change remains an open debate in climatology circles, new data suggests linkages between the tropics and the North Atlantic region. In particular, prominent glacial events and associated climatic shifts in the outer tropics during the early Holocene and late in the “Little Ice Age” period indicate that the LIA was indeed a global event.
For decades, the supporters of CO2 driven global warming have discounted changes in solar irradiance as far too small to cause significant climate change. Though the Sun's output varies by less than a tenth of a percent in magnitude during its 11-year sunspot cycle, that small variation produces changes in sea surface temperatures two or three times as large as it should. A new study in Science demonstrates how two previously known mechanisms acting together amplify the Sun's impact in an unsuspected way. Not surprisingly, the new discovery is getting a cool reception from the CO2 climate change clique.
The supporters of anthropogenic global warming (AGW) claim that they have science on their side. Time and again we are told that the debate is over, the science is settled and consensus among the world's scientists reached. If that is true, why are so many scientists coming forward to oppose and denounce the climate alarmist's theory? To understand the true nature of the climate change debate it is necessary to understand what a scientific theory is and how to judge a theory's validity.
Two of the terms bandied about by global warming alarmists are “unprecedented” and “irreversible.” It is troubling that scientists, who should know better, persist in using these terms even though the history of our planet clearly shows that neither term is accurate. Proof of this inaccuracy is obvious if we look back over the history of Earth—the Phanerozoic Eon in particular—taking the “Grand View” of historical climate change.
Not satisfied with blaming modern civilization for causing rampant climate change, now a small group of scientists are saying that everything went wrong once humans stopped being hunter-gatherers 9,000 years ago. The hypothesis, first advanced in 2003 by University of Virginia palaeoclimatologist William F. Ruddiman, remains controversial even among global warming true believers. Ruddiman now claims to have proven his critics wrong, much to the glee of the blame-humanity-first wing of the eco-activist community.
While the IPCC and global warming alarmists continue to claim climate change is controlled by atmospheric CO2 levels, most knowledgeable scientists will tell you that climate change is caused by variation in Earth's orbit and orientation. These periodic changes in movement and attitude are called the Milankovitch Cycles. A new paper, to be published in Science, confirms that glacial terminations are caused by Earth's orbital cycles, not carbon dioxide.
Increased insolation 20,000 years ago caused deglaciation in the Northern Hemisphere, according to a new report in the August 7, 2009, edition of Science. Further more, it was the onset of deglaciation of the West Antarctic Ice Sheet, which occurred between 14 - 15 thousand years ago, that was the source of sea-level rise at the beginning of the Holocene warming. Such events are often associated with rising CO2 levels by climate catastrophists but the evidence says otherwise.
Two articles in the July 17 edition of Science describe efforts to model Earth's rapidly changing climate at the end of the last glacial period, between 21 and 11 thousand years years ago (ka). After a year and a half of number crunching on Oak Ridge National Laboratory's Jaguar supercomputer, the first results indicate that climate experienced cooling 17 ka, during the Heinrich Event 1 (H1), followed by an abrupt warming at the onset of the Bølling-Allerød Warming 14.5 ka. These abrupt climate changes were accompanied by large changes in the “ocean conveyor belt”: the Atlantic meridional overturning circulation (AMOC). The results suggest that this transition can be viewed simply as the North Atlantic climate response to rapidly changing glacial meltwater flow. The findings call for a paradigm shift in our understanding of abrupt climate change and weakens the threat of “irreversible tipping points” so popular with climate change extremists.
When it comes to climate, the early Paleogene period (~65-34 mya), at the start of the Cenozoic Era, had one of the most Eden like climates of the Phanerozoic Eon. As the Cenozoic progressed a cooling trend set in leading up to the formation of permanent ice caps and the Pleistocene Ice Age we are still experiencing. But before the world started to ice up our planet underwent one of the most dramatic bouts of global warming known to science—the Paleocene Eocene Thermal Maximum or PETM. Recently, global warming activists have tried to liken human CO2 emissions to the cause of the PETM, 55 million years ago. Is it true, that our actions may trigger a sudden sharp rise in global temperature?
Having reported that scientists did not find CO2 responsible for a change in the duration of ice age glacial periods 700,00 years ago, another new report takes a look at the conditions around the last interglacial warm period and our own Holocene warming. Using corals from the south seas paradise of Tahiti to track sea-level changes, researchers probed the mechanisms driving Earth's climate between glacial and interglacial states. Almost as an after thought they added that there is no longer any doubt: changes in sea-level drive changes in CO2, not the other way around.
Around 1.2 million years ago, a shift in global climate began that caused a change in the timing of the alternating warm and cold periods—called interglacials and glacials—that have persisted during the Pleistocene Ice Age. Prior to that time, ice age glacial periods lasted about 40,000 years but since ~700,000 years ago ice-age cycles have lasted for around 100,000 years. Orbital variations, called the Croll-Milankovitch cycles, do exert some forcing on the 100,000 year time scale, but it is relatively weak. Orbital cycles seem to many too feeble an explanation for the change in glacial-interglacial timing. Some scientists have attempted to attribute the timing shift to a drop in CO2 but a new study confirms that carbon dioxide levels were not the cause of the climate shift.
The lingering cool temperatures being experience by much of North America has weather forecasters wondering if we are entering a new Little Ice Age—a reference to the prolonged period of cold weather that afflicted the world for centuries and didn't end until just prior to the American Civil War. From historical records, scientists have found a strong correlation between low sunspot activity and a cooling climate. At the end of May, an international panel of experts led by NOAA and sponsored by NASA released a new prediction for the next solar cycle: Solar Cycle 24 will be one of the weakest in recent memory. Are we about to start a new Little Ice Age?
In a new report in Science, scientists present results matching neither the hypothesis of inter-hemispheric synchrony during the mid to late Holocene nor rhythmic asynchrony, downplaying the importance of global driving mechanisms. It seems that several glacier advances occurred in New Zealand during classic northern warm periods. Understanding the relationship between climate changes in the northern and southern hemispheres during the Holocene, along with their causes, remains a major problem of climate science.